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Number crunching An international paper has called for a greater research focus on dyscalculia, the mathematical equivalent of dyslexia, saying it could lift economic growth.

Dyscalculia is estimated to affect up to seven per cent of the population, making it as common as dyslexia.

But, in a review published today in the journal Science, lead author Professor Brian Butterworth, of the University College London, and colleagues label the disorder a "poor cousin" of its literary stablemate.

"The relative poverty of dyscalculia funding is clear from the figures. Since 2000, the National Institute of Health has spent US$107.2 million (AU$100 million) funding dyslexia research but only US$2.3 million (AU$2.16 million) on dyscalculia," they write.

Butterworth says the lack of funding reflects a view within government that "literacy is more important than numeracy".

"It seems okay in some social circles to say 'I'm hopeless at maths', but not to say 'I am hopeless at spelling/grammar/pronunciation'," says Butterworth.

The authors say low numeracy has a major impact on national economies and growth.

They point to a large UK study that found that low numeracy was more of a handicap for an individual's life chances than low literacy.

"They earn less, spend less, are more likely to be sick, are more likely to be in trouble with the law, and need more help in school. It has been estimated that the annual cost to the United Kingdom of low numeracy is 2.4 billion pounds (AU$3.7 billion)," they say.

An analysis by the Organisation for Economic Co-operation and Development (OECD) showed an improvement of "one-half standard deviation in mathematics and science performance at the individual level implies, by historical experience, an increase in annual growth rates of GDP per capita of 0.87 per cent".

Difficulty in recognising meaning

Butterworth, a professorial fellow at the School of Psychological Sciences at the University of Melbourne, says the disability can affect learners with normal intelligence and normal working memory. But, he adds, it can co-exist with other developmental disorders, including reading disorders and attention deficit hyperactivity disorder (ADHD) "more often than would be expected by chance".

"There are high-functioning adults who are severely dyscalculic, but very good at geometry, using statistics packages, and doing degree-level computer programming," he says.

Dyscalculic learners have difficulty in simple numerical tasks such as enumerating small sets of objects or comparing the numbers of two arrays of dots.

"They fail to access the meaning of the numbers as efficiently; sometimes the link doesn't work as well, but more often the meaning is fuzzier," says Butterworth.

"They do not intuitively grasp the size of a number and its value relative to other numbers."

Learning new arithmetical facts primarily involves the areas in the brain known as the frontal lobes and the intraparietal sulci, on the lateral side of the parietal lobe.

Recent studies have shown dyscalculic brains have reduced activation of the intraparietal sulci during arithmetic and comparing numbers and reduced grey matter in areas of the brain known to be involved in basic numerical processing.

"There is now a very extensive research base in the neural networks involved in arithmetic in typical adults, and some recent work in typical children," says Butterworth. "The research on dyscalculia has revealed abnormalities in the structure and functioning of parts of the known network, but there are actually very few published studies to date, but they are increasing."

Intervention studies needed

However, Butterworth says there is little research on the effects of early and appropriate intervention on sufferers of dyscalculia.

"Further research is needed on the neural consequences of intervention. Even where intervention improves performance, it may not be clear whether the learner's cognitive and neural functioning has become more typical or whether compensatory mechanisms have developed," they write.

"This also leaves open the question as to whether there is a form of dyscalculia that is a delay, rather than a deficit, that will resolve, perhaps with appropriate educational support."

Strengthening the meaningfulness of numbers, especially the link between the math facts and their component meanings, is crucial, they say.

"Effective early intervention may help to reduce the later impact on poor numeracy skills, as it does in dyslexia. Although very expensive, it promises to repay 12 to 19 times the investment."

The authors say learning programs to combat the disorder would have a flow-on use in the wider community.

"The same programs can assist beginning mainstream learners, so one can envisage a future in which all learners will benefit from these developments."